bloody hell that was a long read, according to that file i was just reading on performance engines, and assuming the Z weigh's about? 1150kg? = 5750cc engine can be fitted..... http://www.dotars.gov.au/transreg/vsb/PDF/NCOP3_Section_LA_Engines_3Feb2006.pdf have a squiz at that? im no expect, or good reader, but it seems engineer's reports is all you need. but that said, there are a long list of other things that have to be changed while ur at it, like brakes, driveline to handle new power/touque and a few other nasty little things . Also has a nasty little clause that says this information may still not be correct. So, get on to ur states licencing and find out boys.... i'd like a LS1 between my chassis rails.